Get the absolute value of a number in Javascript

Question

I want to get the absolute value of a number in JavaScript. That is, drop the sign. I know mathematically, I can do this by squaring the square, but I also know that it is terribly inefficient.

x = -25 x = x * xx = sqrt(x) // x would now be 25 

Is there a way in JavaScript to simply abandon the sign of a number, which is more efficient than a mathematical approach?

Answer 1

Do you mean to get the absolute value of a number? Math.abs javascript function is just for that purpose.

 var x = -25; x = Math.abs(x); // x would now be 25 

Here are some examples from the documentation:

 Math.abs('-1'); // 1 Math.abs(-2); // 2 Math.abs(null); // 0 Math.abs("string"); // NaN Math.abs(); // NaN 

Answer 2

Here is a quick way to get the absolute value of a number. This applies in every language:

 (x ^ (x >> 31)) - (x >> 31); 

Answer 3

I think you are looking for Math.abs(x)

https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Math/abs

Answer 4

If you want to see how JavaScript implements this function under the hood, you can check out this post.

Blog post

Here is an implementation based on the chromium source code.

 function MathAbs(x) { x = +x; return (x > 0) ? x : 0 - x; } 

Answer 5

Good for writing only, there might be another simplified method:

 var abs = x => Math.sqrt(x*x)